1. Technical Field
The present invention relates to a semiconductor module.
2. Related Art
A power conversion apparatus is used in equipment utilizing a motor, e.g. a hybrid automobile or electric automobile, in order to achieve low energy consumption. Semiconductor modules including power semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors) are widely used in such power conversion apparatuses. Since heat is generated when a power semiconductor element controls current, a semiconductor module is known that includes a cooling chamber for cooling this power semiconductor element, as shown in Patent Documents 1 to 6, for example.
Patent Document 1: Japanese Patent Application Publication No. 2007-142472
Patent Document 2: Japanese Patent Application Publication No. H10-200278
Patent Document 3: Japanese Patent Application Publication No. 2013-165298
Patent Document 4: Japanese Patent Application Publication No. 2012-142465
Patent Document 5: Japanese Patent No. 5381561
Patent Document 6: Japanese Patent Application Publication No. 2011-171686
However, the cooling chamber cooling a layered substrate on which the power semiconductor element is mounted has a linear expansion coefficient that differs from that of the layered substrate by several times. When heat cycle testing is performed on such a semiconductor module, thermal stress occurs in the solder layer bonding this layered substrate and the cooling chamber, causing cracking and/or breaking.